package tech.yuliu.utils;

import org.springframework.stereotype.Component;

import java.util.*;

@Component
public class Levenshtein {
    private int compare(String str, String target) {
        int[][] d;              // 矩阵
        int n = str.length();
        int m = target.length();
        int i;                  // 遍历str的
        int j;                  // 遍历target的
        char ch1;               // str的
        char ch2;               // target的
        int temp;               // 记录相同字符,在某个矩阵位置值的增量,不是0就是1
        if (n == 0) {
            return m;
        }
        if (m == 0) {
            return n;
        }
        d = new int[n + 1][m + 1];
        for (i = 0; i <= n; i++) {                       // 初始化第一列
            d[i][0] = i;
        }

        for (j = 0; j <= m; j++) {                       // 初始化第一行
            d[0][j] = j;
        }

        for (i = 1; i <= n; i++) {                       // 遍历str
            ch1 = str.charAt(i - 1);
            // 去匹配target
            for (j = 1; j <= m; j++) {
                ch2 = target.charAt(j - 1);
                if (ch1 == ch2 || ch1 == ch2 + 32 || ch1 + 32 == ch2) {
                    temp = 0;
                } else {
                    temp = 1;
                }
                // 左边+1,上边+1, 左上角+temp取最小
                d[i][j] = min(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + temp);
            }
        }
        return d[n][m];
    }

    private int min(int one, int two, int three) {
        return (one = Math.min(one, two)) < three ? one : three;
    }

    /**
     * 获取两字符串的相似度
     */

    public float getSimilarityRatio(String str, String target) {
        return 1 - (float) compare(str, target) / Math.max(str.length(), target.length());
    }

    public List<String> getMostSimilar(List<String> stringList, String target) {
        HashMap<String, Float> strWithSimilarity = new LinkedHashMap<>();
        for (String str : stringList) {
            strWithSimilarity.put(str, getSimilarityRatio(str, target));
        }
        Float maxSimilarity = getMaxValue(strWithSimilarity);
        List<String> result = new ArrayList<>();
        for (String key : strWithSimilarity.keySet()) {
            Float value = strWithSimilarity.get(key);
            if (value.equals(maxSimilarity)) {
                result.add(key);
            }
        }
        return result;
    }

    /**
     * 求Map中Value(值)的最大值
     */
    private Float getMaxValue(HashMap<String, Float> map) {
        if (map == null)
            return null;
        int length = map.size();
        Collection<Float> values = map.values();
        Object[] obj = values.toArray();
        Arrays.sort(obj);
        return (Float) obj[length - 1];
    }
}